Submitted to: Proceedings of Plant Growth Regulation Society of America
Publication Type: Proceedings
Publication Acceptance Date: 10/1/2003
Publication Date: 12/1/2003
Citation: Curry, E.A. 2003. Does preharvest treatment with NAA cause ripening in climacteric tree fruit? Proceedings of Plant Growth Regulators Society of America. December. p. 38.
Technical Abstract: 1-Naphthaleneacetic acid (NAA) has been an effective bioregulator for the control of preharvest fruit abscission on apples and pears for more than 60 years. Although it has been reported NAA at super-optimal rates for control of preharvest drop may advance ripening, data reported herein suggest this may not be the case. Like ethylene, NAA promotes fruit abscission in the early spring, presumably by an ethylene-induction mechanism. Because ethylene also stimulates fruit ripening in the fall, is it tempting to assume NAA acts similarly on mature fruit tissue, even though ethylene promotes whereas NAA inhibits fruit abscission. Opposing fruit abscission responses to preharvest ethylene or NAA, therefore, may be due to the following: 1) differential tissue sensitivity or response to NAA; 2) differential auxin status across the abscission zone created by the changing absorptive surface areas of leaves and fruit; or 3) because NAA inhibits ethylene in the stem abscission zone and, may do so in fruit tissue as well. Indeed, that NAA advances ripening may just be a perception based on the artificial retention of fruit of advanced maturity.